Abstract: The rotary feed system of high-performance multi-coordinate CNC machine tools, such as swing head and turntable, is mostly directly driven by permanent magnet synchronous servo motor, and its control problem is more complicated than the conventional feed system. Therefore, it is of great significance to establish a more scientific mathematical model suitable for direct-drive permanent magnet synchronous motor to improve the control level of rotary feed system. In this paper, a state space model of direct-drive permanent magnet synchronous motor based on vector control is proposed, and the controllability, observability and stability of the system are analyzed and calculated by using modern control theory, the poles of the system are configured, and the system simulation is carried out by using Simulink, which provides a theoretical basis and analysis method for the design and analysis of rotary feed servo system of CNC machine tools.
Keywords: rotary feed; Direct drive; Permanent magnet synchronous motor;
China Library ClassificationNo.: TP39 1 Document IdentificationNo.: A DocumentNo.:1009-0134 (2007) 08-0040-05 State Space Model and Performance Analysis of CNC Machine Tool Rotary Feed System Zhang Ao, (Tsinghua University Department of Precision Instruments and Machinery, Beijing/KLOC) Therefore, it is of great significance to establish a PMSM mathematical model suitable for direct drive more scientifically for improving the control level of rotary feed system. Therefore, a PMSM modeling method of PMSM state space equation based on vector control is proposed. The controllability, observability, stability and pole assignment of the system are analyzed by modern control theory. The system simulation is completed with Simulink. This method provides a theoretical basis and analysis method for the design of rotary feed servo system of CNC machine tools. Keywords: rotary feed; Direct drive; PMSM； State space equation 0
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The rotary feed servo system of high-performance CNC machine tools, especially the direct drive servo system (that is, all mechanical intermediate transmission links from the motor to the actuator or load are cancelled, and the length of the transmission chain is shortened to zero. Permanent magnet synchronous motor (PMSM) is widely used as the control object. Its advantages are simple structure and reliable operation. By adopting structural measures such as high remanence induction, high coercivity and rare earth magnets, the overall size of DC motor is reduced by about 1/2, the weight is reduced by 60%, and the rotor inertia can be reduced to 1/5 of DC motor. [2] It should also be noted that due to the existence of the transmission link, the traditional drive system has less stress on the control link, and the sensitivity of the system to disturbance is relatively low, while the load of the direct drive servo system is almost directly connected with the control link, and there is no buffer of the transmission chain, so the control link has greater stress and is sensitive to disturbance, which may affect the dynamic performance of the system; At the same time, the swing head and turntable are characterized by bearing low speed and heavy load, so the low speed stationarity under heavy load is also an important issue in system design. Therefore, for the direct drive system of rotary feed such as turntable and pendulum of CNC machine tools, its control problem is more complicated than that of conventional feed system. In engineering practice, the classical three-loop control method based on vector transformation control is usually used to control the system. The control model is based on the classical control theory, that is, the system is described by the transfer function, with a single variable (such as speed) as the output and directly related to the input (such as voltage). But in fact, the system contains other independent variables besides the output, and the differential equation or transfer function is not convenient to describe these internal intermediate variables, so it cannot contain all the information of the system and completely reveal all the motion states of the system. If the state space method of modern control theory is applied to analyze the system, its dynamic characteristics are described by a group of first-order differential equations composed of state variables, which can reflect the changes of all independent variables of the system, determine all internal motion states of the system, and handle initial conditions conveniently. Therefore, it can characterize the relationship between the system and the variables in the system more comprehensively, especially for nonlinear, multi-input and multi-output systems. [5] To sum up, the rotary feed direct drive servo system is a complex system with strong coupling and nonlinearity, and it is more scientific and effective to use the state space method to model. On the basis of vector control, the state space model of permanent magnet synchronous motor is established by state space method, and the model is comprehensively analyzed by various methods of modern control theory, which lays a solid foundation for further application of advanced control methods to control the system. Mathematical model of 1 PMSM We consider the sinusoidal permanent magnet synchronous motor system. The motor has a sinusoidal back electromotive force waveform, and its stator voltage and current are also sinusoidal. Assuming that the motor is linear, the parameters do not change with temperature, ignoring hysteresis and eddy current loss, and the rotor has no damping winding. Based on the conclusion of motor unification theory, the stator flux linkage equation of permanent magnet synchronous motor in rotor coordinate system (D-Q shafting) is as follows:
(1) where:-coupling flux linkage of rotor magnetic steel on stator; Ld, LQ-the main inductance of the direct axis and the quadrature axis of the permanent magnet synchronous motor; -Direct axis and quadrature axis components of stator current vector. The PMSM stator voltage equation is: (2) where-D and Q axis components of the stator voltage vector us; W—— Electrical angular frequency of the rotor. The torque equation of PMSM is: (3) The motor torque coefficient Kt is: KT = PMYR. In addition, the motor system must satisfy the basic equations of motion: (4) where n is the motor speed; Wr- mechanical angular velocity of rotor, w = pmwrTd, TL- electromagnetic torque and load torque of motor. The state equation of modern control theory is used to model the permanent magnet synchronous motor. If vector control is adopted, id=0 is generally required, but it is unreasonable that md and id do not appear in the state equation. Because in the control mode of id=0, only the value of id is required to be equal to 0, but the actual value of id is not always equal to 0 (especially in the dynamic process). At the same time, the actual value of ud will not be equal to 0. Therefore, ia must also be regarded as a state variable and md as a control variable, which is controlled by the controller according to the values of all state variables (including id). Therefore, take the state variable and q as the rotor position angle. If the expression (1) is brought into the second expression of the expression (2), the state equation of the permanent magnet synchronous motor can be obtained from the expressions (3) and (4): (5) Therefore, the system is a nonlinear time-varying system, and the coefficient matrix contains cross multiplication terms of wr, id and iq state variables, so it is necessary to decouple the system. Taking ud and uq as control variables and load torque TL as disturbance, therefore, if it is put forward separately, it will be systematized in the form of =AX+BU+B0TL. The original systematization is as follows: (6) 6) Analysis of 2 PMSM system. The parameters of PMSM are as follows: the system state space equation is: 2. 1 polynomial model, and the state space model is transformed into polynomial model, and the system transfer matrix is: 2.2 controllability sum. The necessary and sufficient condition for the state to be completely observable is that the rank of the observable matrix is n, and it can be calculated that the controllable matrix rank of the system is 4 and full rank, then the state of the system is completely controllable. If the rank of the observable matrix of the system is 4 and full rank, the state of the system is completely observable. 2.3 Stability analysis of control system For the system represented by state space model, the necessary and sufficient condition for system stability is that all eigenvalues of system matrix A have negative real parts. Eig (a)' =1.0e+002 * [0-1.2069-0.8066i-1.8066i-2.12] Because 2.4 Pole configuration of multi-input control system The basic idea of pole configuration of multi-input system is to obtain a state feedback first, so that its closed-loop system can control a certain input (such as the first input), and then carry out pole configuration according to the method of pole configuration of single-input system [5]. Figure 1 block diagram of closed-loop system The expected pole with pole configuration is:1.0e+002 * [-0.1-1.2069-0.8066i-1.2069+0.8066. , can be obtained from the system, n=4, m=2, u 1+u2=4, and a is the last line vector of Q- 1. (2) First, configure the poles according to the controllable standard. Pole assignment of single input system. The characteristic polynomial of is, and the expected characteristic polynomial is, then the gain matrix is: (3) the controllable standard transformation matrix T, that is, the gain matrix returns to the original coordinate system (4). The state feedback of the pole configuration of the original system (A, B) is: 2.5 The response of the position state vector of the system simulation system to the step signal: Figure 2 The step response of the position state vector before the pole configuration; Fig. 3 step response of position state vector after pole assignment; Response of system position state vector to speed signal (dotted line is input position signal and solid line is output position signal): Figure 4: Speed signal tracking curve before pole configuration; Response of system position state vector to sine signal (dotted line is input position signal and solid line is output position signal) Figure 5: Speed signal tracking curve after pole configuration 6: Sine signal tracking curve before pole configuration 7: It can be seen from pole configuration that the system is stable, its response to various input signals is greatly improved, and it has the following characteristics. 3. It is concluded that the system represented by the state space equation can relate the state of the system with the input and output of the system, establish the relationship between the internal variables of the system and the external inputs and measured outputs, and save the information of the internal characteristics of the system, so the model is more accurate and scientific. A method of establishing a complete state space model of permanent magnet synchronous motor based on vector control is proposed. According to this model, the performance of the system is analyzed and calculated by using various methods of modern control theory. Analysis shows that the system has complete controllability, complete observability and critical stability. The system is stabilized by state feedback pole assignment, so that the state variables have good tracking performance for the input signals. It provides effective methods and ideas for further analysis and design of control system.
References: [1] Ouyang Liming. MATLAB control system design [M]. Beijing: National Defense Industry Press, 200 1. [2] Zhang Chongwei, Li,. Motion control system [M]. Wuhan: Wuhan University of Technology Press, 2002. [3] Li Sandong, Xue Hua. (2):115-120. [4] Yang Ping, Ma Ruiqing, An. Modeling and simulation method of permanent magnet synchronous motor control system based on Matlab [J]. Journal of Shenyang University of Technology, 2005, (4): 195-65433. Du Jingyi. Theoretical basis of modern control [M]. Peking University Publishing House, 2006. [6] Sun Liang. MATLAB language and control system simulation [M]. Beijing: Beijing University of Technology Press, in 2006, under the situation that China's logistics management is gradually moving towards socialization and supply chain, it is necessary to combine the logistics operation and management practice of specific enterprises, according to the basic principles of lean logistics and the informatization of enterprises, and through theoretical and applied research, on the basis of the prototype system of lean supply chain logistics management, constantly revise and improve, and constantly carry out research and practice to promote the development of lean supply chain logistics management information system of Chinese manufacturing enterprises. Reference: [1] wuyue. On lean logistics system [J]. China Circular Economy, 20065438+0 (5):1-13. [2] (America) James P. Womach, (England) 1999. [3] Richard Wilding. Thin, thinner and thinnest [J]. International journal of logistics and logistics. Logistics Management1996,25 (3/4) 20. [4] Wang Zhitai. Logistics engineering research [M]. Beijing: capital university of economics and business Publishing House, 2004. [5] Tian Yu, Zhu Daoli. Lean logistics [J]. Logistics technology, 1999 (6 hours. Calculation model of logistics circulation and response time in supply chain [J]. Trading System of World Summit on Information Society, 2006,5 (4): 643-650. __
Typical application of PLC in numerical control transformation of machine tools
School of Mechanical and Electronic Engineering, Hebei University of Science and Technology, Shijiazhuang 050054.
This paper discusses the concrete scheme and general steps of NC transformation of machine tools by using programmable controllers, introduces the concrete process of transformation by taking Siemens S7-200 series programmable controllers as an example, and expounds the application effect of NC transformation of machine tools and its future social and economic benefits. Keywords: programmable controller; Machine tool; Numerical control transformation
China Library Classification Number: TG5 1 Document ID: A Document Number:100320794 (2007)1120147202.
Typical application of PLC in numerical control transformation of machine tools. This paper discusses how to reform the machine tool by using programmable controller (PLC), and introduces in detail the whole process of reforming the cutting machine based on Siemens S7-200 PLC. Finally, the function of numerical control transformation and its benefits are expounded. Key words: programmable logic controller (PLC); Machine tool; Numerical control transformation 0
Some existing machine tools in China still adopt the traditional relay-contactor control mode. These machine tools have many contacts and complicated circuits. After years of use, they have many faults, large maintenance, inconvenient maintenance and poor reliability, which seriously affect normal production. Although some old machine tools can still work normally, their accuracy, efficiency and automation can no longer meet the current production process requirements. It is imperative to reform these machine tools. Transformation is not only the need of enterprise resource reuse and sustainable development, but also the need of adapting to new production technology and improving economic benefits.
1 The solution is an effective means to transform the old machine tool control system with PLC. After adopting PLC control, the wiring number of machine tool control circuit is greatly reduced, the failure rate is greatly reduced, the stability and utilization rate of equipment operation are improved, the reliability is enhanced, and the maintenance intensity is reduced. When the machining program of the machine tool changes, it is more convenient to modify the PLC program to carry out new machining, which is helpful to improve the application of the machine tool. Because the machine tool has communication function, after the machine tool is reformed by using programmable controller, it can be networked and communicated with other intelligent devices, and can be connected to the factory automation network as needed in the further technical transformation and upgrading in the future.
2. The transformation process, steps and application examples (1) deeply understand the working process of the original machine tool, analyze and sort out its basic control mode, completed action sequence and condition relationship, as well as related protection and interlock control, and fully communicate with the actual operators as far as possible to understand whether it is necessary to improve the control operation of the existing machine tool to improve accuracy, operability and safety; If necessary, it will be implemented in the subsequent design. (2) According to the results of analysis and sorting, determine the input and output devices required by users. Because it is the transformation of the old machine tool, on the premise of ensuring the completion of the process requirements, the input and output equipment of the original machine tool, such as buttons, travel switches, contactors, solenoid valves, etc. , is the maximum utilization, reduce the cost of transformation. (3) PLC selection. According to the number and types of input and output devices, determine the required IPO points. When determining the number of IPO points, we should leave a margin of about 20% to adapt to the future changes in production technology and leave room for system transformation. According to the number of IPO points, an empirical formula is used to estimate the memory capacity: total memory words = (switch input points+switch output points) × 10+ analog points × 150. After estimating the number of words in the memory, leave a 25% margin. Accordingly, select the appropriate model. (4) Design and compile the IPO allocation table and draw the IPO wiring diagram. It should be noted that the same type of input points or output points should be concentrated and distributed continuously as much as possible. (5) Program design. The original machine tool relay control circuit diagram can be modified and improved. After the program design is completed, simulation debugging should be carried out. (6) After the simulation debugging, the on-site system debugging is carried out. Check the problems in debugging one by one until the debugging is successful. Finally, the technical data should be sorted and filed. Figure 1 IPO wiring diagram The following is the numerical control transformation process of a saw blade cutting machine. The control process of the machine tool is as follows: (1) spindle motor control. Start, stop; (2) Feed motor control. The workbench is longitudinally fed to the position tangent to the saw blade, and then the workbench is transversely fed quickly. After completion, the workbench moves slowly and retreats. During this period, the main workbench of the saw blade rotates by a sawtooth angle at variable speed, and the two moves are interpolated to form a sawtooth arc. (3) Starting control of cooling pump motor, related protection and interlock control, over-travel protection in all directions of workbench, interlock control in all directions, etc. Determine the required user input P output device. According to the analysis of the hardware conditions of the equipment, there are six buttons on the panel, which need to occupy six digital input ports, a BCD dip switch occupies four input ports, a linear grating ruler occupies three input ports, and a three-position status knob occupies two input ports. The actuators are three stepping motors and two asynchronous motors, of which three stepping motors need eight digital output ports, and the grinding wheel main motor and cooling pump each need 1 output ports. In order to ensure safety, the thermal relay is directly connected to the output of PLC instead of the input; The total number of input points is 15, and the number of output points is 12. Considering that there should be a margin of about 20%, the number of IPO points should be above 30 points. So we choose Siemens S7-200 series 226 PLC, with 24 input points, 16 output points and 40 IPO points. Prepare the IPO allocation table (see table 1) and draw the IPO wiring diagram (see figure1); With the help of the original relay control circuit diagram of machine tool, the program is designed and STL structured programming language is written. Simulation debugging and on-site system debugging, complete the filing of technical data. Table 1 IPO allocation table input-output I0. 0bcdip switch 1 Q0. 0 W axis CP terminal I0. 1 BCD dual in-line switch 2-bit Q0. 1 X axis PY axis CP terminal I0. 2bcdip switch 3-bit Q0. 2 W axis direction terminal I0. 3bcdip switch 4-bit Q0. 3 W axis free end I0. 4. Start Q0. 4 X-axis direction end point I0. 5 Pause Q0. 5 X axis free end I0. 6. Phase A input Q0 of grating ruler. 6 y-axis direction end point I0. 7 Phase B input Q0 of grating ruler. 7 y-axis free end I 1. 0 grating ruler z phase reset Q 1. 0 main motor relay I65438. +0. 1 saw blade diameter input confirmation Q 1. Cooling pump relay I 1. 2 Enter the grinding wheel diameter and confirm Q 1. 2 alarm indicator I 1. 3 three-position status knob input 1 Q 1. 3 Power-on indicator I65438. After 38+0. 5 cooling pump start I 1. 6 emergency stop 3, the effect can realize flexible automation of processing, and the efficiency is 5 ~ 6 times higher than that of the traditional saw blade machine. The processed sawtooth has high precision and small size dispersion, which improves the strength of sawtooth. It has self-adjustment functions such as automatic alarm, automatic monitoring and compensation, and can realize long-term unattended processing. Because the saw blade adopts new alloy steel, the cost of repairing worn teeth is very high. After adopting this saw blade machine, it saves considerable maintenance cost for the factory and really improves the efficiency of the factory. Conclusion Using PLC to reform the traditional machine tool can effectively solve the complex, precise and changeable parts processing problems, meet the requirements of multi-variety, small-batch high-quality, efficient and flexible production methods, and meet the needs of rapid upgrading of various mechanical products. At the same time, it saves a lot of equipment renovation costs for enterprises, improves their economic and social benefits, enhances their product competitiveness, and makes it easier for enterprises to survive and develop in a highly competitive market environment. References: [1] Chen. Electrical control and programmable controller [M]. Guangzhou: South China University of Technology Press, 200 1. [2] Zhang Xinyi. Design of Economical CNC Machine Tool System [M]. Beijing: Machinery Industry Press, 1994. About the author: Shao Xiaoxi.
Remote management of CNC machine tools based on network
Wang Huifen, Liu Tingting, Zhang Youliang (School of Mechanical Engineering, Nanjing University of Science and Technology, Jiangsu 2 10094)
Networked manufacturing is the main mode of production in 2 1 century, and it is inevitable to manage CNC machine tools by using network technology. On the basis of analyzing the requirements of networking and remote management of CNC machine tools, a scheme of networking and remote management system of CNC machine tools based on TCP/IP is proposed, which can be seamlessly integrated with other information management systems of enterprises. The structure and functions of the system are introduced in detail, and an application example is given.
Keywords: networked manufacturing; CNC machine tools; Remote Management China Library ClassificationNo.: TG659 Document IdentificationNo.: A.
ArticleNo.:1001-3881(2007)10-070-4 Based on the analysis of the requirements of networking and remote management of CNC machine tools, this paper puts forward a networking scheme and remote management system based on TCP/ip2, which can be used with other CNC machine tools in enterprises. Then the architecture and main functions of the system are discussed. An application example is introduced. Keywords: networked manufacturing; CNC machine tools; Remote management 0
Introduction Networked manufacturing is the main production mode of manufacturing industry in 2 1 century. Networked design and manufacturing system is an open, multi-platform and collaborative system composed of various, heterogeneous and distributed manufacturing resources using computer networks in a certain interconnected way, which can respond to changes in market demand in a timely and flexible manner. It is characterized by dynamic alliance in organization, and its goal is to connect the existing various geographically or logically distributed manufacturing systems to the computer network, so as to improve the information exchange and cooperation ability among various units, and then realize the sharing of various resources, quickly design and manufacture products, and respond to the market demand. It is the main technical measure for manufacturing enterprises to shorten product development cycle, improve product quality, reduce product cost and enhance competitiveness in the 2 1-3 century. The communication between CNC machine tools and computers is the basis and necessary condition to realize integrated control and management of manufacturing equipment, and it is also one of the keys to realize networked manufacturing. With the deepening of the application of numerical control technology and the continuous development of computer technology and network technology, the number of numerical control machine tools in enterprises is increasing. The traditional single-machine management mode can no longer meet the needs of enterprise development because of backward technical means, low production efficiency and high management and maintenance costs, so it is inevitable to manage numerical control machine tools by using network technology [4]. After more than 20 years of development, DNC technology of CNC machine tool network in China has also experienced a difficult process from paper tape to single machine, to simple network, and finally to advanced network. Paper tape mode has been basically completely abandoned; When the number of machine tools is small, some users are still using stand-alone communication mode; When the number of machine tools develops to a certain number, machine tool users generally adopt network DNC [5]. At present, there are two main structures of the network DNC of CNC machine tools in China: one is that a single computer corresponds to a single machine tool, and these computers are connected through a local area network; The other is that a single computer corresponds to multiple machine tools, most of which are based on RS2232 serial communication or foreign communication software products [6- 10], and some are based on TCP/IP domestic software [1 1- 13]. However, with the development of market economy and enterprise informatization, enterprises use a variety of information management systems, such as ERP, PDM, MES, CAD /CAPP /CAM, etc. Information sharing between various systems must also be considered to avoid information islands. Therefore, it is imperative to use integrated DNC technology to manage CNC equipment group. On the basis of analyzing the requirements of networking and remote management of CNC machine tools, a scheme of networking and remote management system of CNC machine tools based on TCP/IP is proposed, which can be seamlessly integrated with other information management systems in enterprises. The implementation technology and application examples of this system are introduced in detail.
1 remote management system structure of CNC machine tools11system requirements analysis At present, in the process of implementing networked manufacturing, more and more enterprises have gradually implemented enterprise information engineering, and single-machine CNC machine tools have become the bottleneck restricting enterprises to respond to the market quickly. In order to better meet the needs of production development, it is urgent to transform the CNC machine tools of enterprises into networks and realize the remote management of CNC machine tools and workshops by information systems. The design of remote management system for CNC machine tools needs to meet the following requirements: (1) Openness. With the development of new technology, the system should be extensible and customizable, and it is easy to add and update the functions of the system. The configuration of the system should have good universality, compatibility, portability and interoperability. (2) flexibility. The system supports a variety of operating systems (Windows98 /NT 4 10 /2000), which should be adapted to the controller type, number of devices and tasks.